A trunking communication system is a specific industry application orientated private wireless communication system which is developed for meeting command requirements of industry users. In the trunking communication system, a large number of users share a small number of wireless channels. The trunking communication system is a multipurpose and high-efficient wireless communication system which takes commanding and dispatching as its main application. The trunking communication system has an expansive market in government department, public security, emergency communications, electricity, civil aviation, petrochemical industry, military and other fields.
The trunking communication system is essentially featured by adopting a point-to-multipoint half-duplex communication mode, sharing downlink radio resources by multiple users, having fast commanding and dispatching capabilities like group calling and single calling, high requirement for network reliability and security, and having capabilities like fail-soft and direct mode operation. Because the trunking communication system is applied mostly to military, public security, emergency situation and so on, broadband wireless access system is required to have higher fault-tolerant processing capacity and redundancy backup capacity. Under a condition that a network side (core network) fails, trunking users should be still able to communicate, so as to weaken impact brought by the fault of the network side to the greatest extent and minimize risk. The current broadband digital trunking communication system based on a Time Division-Long Term Evolution (TD-LTE) technology of Datang Telecom usually uses a method that a base station serves as the temporary core network to realize the fail-soft, but no feasible solution about how to select a proper base station as the temporary core network has been presented.